Method and device for handling articles

ABSTRACT

A method of handling articles in which at least one mechanical tool conveys the article or plays a part in transferring the article, and according to which at least one jet of gas under pressure is blown through a duct passing through the mechanical tool, and also according to which the article is held in position on the mechanical tool while limiting contact therewith, by means of the said jet of gas.

BACKGROUND OF THE INVENTION

The invention relates to a technique for handling articles. Moreparticularly, the invention deals with techniques for handling articleswhile they are being made and more specifically articles which are at ahigh temperature.

DESCRIPTION OF THE BACKGROUND

Although the invention is not limited to this type of industry, it willbe described with reference to the industry which deals with themanufacture of glass containers of the bottle or flask type. To make iteasier for the reader to understand, the invention will morespecifically be described with reference to "pushers". Pushers are toolsallowing the bottles as they leave the mould in which they were formedto be transferred to a conveyor of the rolling belt type which takesthem away, for example, towards an annealing tunnel.

These pushers usually consist of several compartments in which severalbottles are accommodated at the same time. Their use consists, as soonas the bottles are released from the moulds, in moving the said pusherstowards the bottles in order to push the latter towards the conveyorbelt. Each bottle finds itself in a compartment of the pusher designedfor this purpose.

As the pusher pushes the bottles, there is always, a priori, contactbetween the pusher and the bottles, and the risks of this contact aregenerally lessened by the presence of contact materials such as carbonor special resins fixed to the metal walls of the pushers. Such contactis to be avoided because the bottles, owing to their temperature at thisstage in the production, may become marked, which leads to defects suchas scratching, glazing. These defects lead either to a reduction in themechanical strength of the articles, or possibly to them being scrapped.

What is more, the fact that the bottles are moved along by being pushed,without being held entirely firmly by the walls of the compartments ofthe pushers, may lead to unsteady movement, or even to the bottlesfalling over and therefore breaking, or alternatively to the productionmachine becoming covered in glass.

The creation of suction by means of a vacuum in order to pull thebottles onto the walls of the pusher as they are being transferred fromone place to another has already been proposed. One such technique doesindeed allow a bottle to be held correctly in position while it is beingtransferred but contributes to increasing the risks of defects due tothe contact with the walls of the pushers. This is because the bottlesthus pulled have at least one generatrix in contact with one wall of thepusher, and generally two, given that the bottle is wedged into a cornerof the pusher. Another technique, especially described in U.S. Pat. No.4,927,444 consists in blowing a jet of air from an orifice placed on thepusher on a wall facing the point at which a bottle is to be held inplace. According to this technique, the bottles are held in placeagainst the walls of the pusher by the pressure of the jet of air whichpresses the bottles against the walls. This technique has the samedrawbacks as the technique described earlier because it accentuates thecontact between the bottles and the walls, and therefore the risks ofdefects appearing.

SUMMARY OF THE INVENTION

The subject of the invention is a method of handling articles whichgives precise positioning of the article during handling while at thesame time avoiding as far as possible any contact with the tools. In thecase of a pusher, the object of the invention is thus to hold a glassbottle firmly in position in a pusher while at the same time limitingthe contacts between the walls of the pusher and the bottle.

This object is achieved according to the invention using a method ofhandling articles in which at least one mechanical tool conveys thearticle or plays a part in transferring the article, and according towhich at least one jet of gas under pressure is blown through a ductpassing through the mechanical tool, and the article is held in positionon the mechanical tool while limiting contact therewith, by means of thesaid jet of gas. The method according to the invention is moreparticularly suited to handling glass articles which are at a hightemperature, that is to say a temperature which may especially lead todefects in the article upon contact with a tool. This is because the jetof gas blown through the duct which, logically speaking ought to pushthe article away, may create a suction thereon when the said article isseparated from the said orifice by a given distance. This distance quiteobviously depends on various parameters of the jet associated especiallywith the pressure, the flow rate of gas and with the dimensions of theorifice of the duct and the diameter of the object. When this distancedecreases further, that is to say as the article comes up very close tothe orifice of the duct and therefore the wall of the tool, the jet ofgas again acts to push it away. This reduction in the distance takesplace automatically, for example, in the case of a pusher, because onthe one hand the pusher is advancing towards the bottle and because onthe other hand the bottle is being sucked towards the pusher.

DETAILED DESCRIPTION OF THE INVENTION

The method according to the invention therefore makes it possible, usinga suction phenomenon, to hold the article in position on the mechanicaltool while at the same time avoiding as far as possible any contacttherewith, because the jet of gas resumes a pushing-away function whenthe orifice-article distance becomes very small. In the case of apusher, contacts between the tool and the article may remain, but theseare only point contacts and occur only infrequently in contrast to thetechniques of the prior art discussed earlier where permanent contactsexist along at least one generatrix of the body of a bottle. These pointcontacts may be due to slight wobbling of the bottle, as it is notpossible for the latter to be perfectly stable as it is being movedalong. The results obtained according to the invention, that is to sayholding an article in position without contact with the walls, are verygood when the article comes up directly opposite the orifice of theduct. It has become apparent that the results are just as satisfactorywhen the article does not come up directly opposite the orifice but isslightly offset or offcentred with respect to the said orifice.

However, and especially in the case of the pusher, it may prove trickyto manage simultaneously the movement of the tool and the jet of gas;this is because whereas the pusher approaches the bottles in order todrive them along, the jet of gas under pressure tends to push thebottles away as long as the critical distance has not been reached, thatis to say the distance separating the orifice from the bottle beyondwhich the said bottle experiences a phenomenon of suction.

According to a first alternative form of the invention, provision ismade to initiate the blowing of the gas when the article reaches thesaid critical distance, that is to say when, for example, the pusher isclose enough to the bottle for a phenomenon of suction to occur. Thissolution is satisfactory but may lead to an increase in cost because itis accompanied, for example, by sensors determining the position of thearticle and connected to devices for starting the blowing of gas. Inaddition, one and the same pusher may convey several bottlessimultaneously, the said bottles having relative positions with respectto the pusher which may differ from one bottle to another. It maytherefore be necessary to design a device which manages the air blowingsindependently of one another for each of the bottles; such a device iseven more complicated and therefore more expensive.

According to a second alternative form of the invention, provision ismade to blow the jet of air through a duct arranged relative to the wallof the mechanical tool on which it emerges in such a way as to create aCoanda effect on the wall of the mechanical tool. According to thissecond alternative form, the flow of air blown through the orifice ofthe duct runs along the wall of the tool and therefore no longer pointstowards the article. In the case of a pusher, the air blowing maytherefore start before the pusher has approached the bottle, without therisk of the bottle being pushed away. There is then a phenomenon ofsuction irrespective of the distance separating the bottle from theorifice, this phenomenon becoming appreciable when the bottle becomesclose to the orifice. However, when the distance separating the articlefrom the orifice of the duct reduces further, the jet of gas ends uppushing the article away so that the article is held in position withoutin any way having contact with the walls of the mechanical tool.

The duct is advantageously made in such a way that the flow of gas runsalong the wall in a direction similar to the relative path followed bythe article with respect to the tool. For example, if in the case of apusher it is desired to hold the bottle in a corner formed by two wallsof the said pusher, the duct will be produced in such a way that theflow of gas leads off towards this corner. In this way, this gaseousflow does not disturb the advancement of the article. Moreover, it hasbecome apparent in some cases that this gaseous flow may alsoadvantageously play a part in driving the article along and thereforeassist with its movement.

Also, with the objective of not disturbing the movement of the articlewith respect to the tool and by contrast of assisting or even orientingthis movement, provision is advantageously made to blow at least twojets of gas acting simultaneously or in succession on one and the samearticle or on different articles. The invention also proposes a devicefor implementing the method which has just been described. According tothe invention, this device for handling articles includes a mechanicaltool, such as a pusher, for conveying the article or playing a part intransferring it, at least one wall of the tool being pierced with atleast one duct connected to a source of gas under pressure and theorifice of the said duct being placed such that the distance separatingit from the article decreases during at least a first phase in thehandling. The device thus described therefore makes it possible, byblowing a jet of air, to create a phenomenon of suction on the articlewhich will therefore start off by moving close to the orifice of theduct.

According to a preferred form of the invention, in order to create aCoanda effect on the wall of the mechanical tool, the direction of theduct forms an angle with the surface of the wall through which itpasses. This angle needs to have a minimum value which depends on thepressure of the gas and the geometric characteristics of the wall and ofthe duct.

In order to obtain a Coanda effect, the orifice of the ductadvantageously has the shape of a slit or alternatively consists of aset of holes, preferably aligned holes.

In addition to the use of the method for improving the efficiency of thepushers, the invention envisages other applications including thoselisted below without implied limitation.

These are first of all an application of the method for the alignment ofbottles on a conveyor. For such an application, the invention allowsgood positioning of the bottles with little or no contact between thebottles and the wall of the tool or "alignment device" and, furthermore,in cases where a Coanda effect is created, the gaseous flow contributesto the advancement of the bottles as was explained earlier.

Another application deals with the transportation of gobs after thesehave been cut. The gobs are "drops" of glass obtained from molten glassand which are brought to the forming devices using "troughs". Accordingto the invention, the troughs are associated with ducts of a gas underpressure which allow the position of the gobs to be controlledaccurately, limiting their contact with the troughs. The inventiontherefore allows good control over the position in which the gobs arriveat the forming device.

Other advantageous features and details of the invention will becomeclear below from the description of embodiments of the invention givenwith reference to the figures which represent:

FIG. 1, a diagram of a device illustrating the principle of theinvention,

FIG. 2, a diagram of a pusher,

FIG. 3, a diagram of part of a pusher according to the invention,

FIGS. 4, 5, curves illustrating the results obtained with the device ofFIG. 3,

FIG. 6, an alternative form of FIG. 3,

FIG. 7, the results obtained according to this alternative form,

FIG. 8, a diagram of part of a pusher according to another embodiment ofthe invention,

FIG. 9, the results obtained according to the diagram of FIG. 8, in thecase of FIG. 10,

FIG. 10, an alternative form of FIG. 8,

FIG. 11, another alternative form of FIG. 8,

FIG. 12, the results obtained according to the alternative form of FIG.11,

FIG. 13, the results obtained according to another alternative form ofFIG. 8,

FIG. 14, a diagram of an alternative form according to the invention,

FIG. 15, a diagram of a pusher according to the invention,

FIGS. 16 and 17, two diagrams representing the movement of the pusheraccording to FIG. 15.

Represented in FIG. 1 in side elevation is a diagram of a device makingit possible to demonstrate the phenomenon described in the application.This simplified device is composed of a cylinder 1 of diameter 30 mmthrough which there passes a passage 2 of circular section with adiameter of 1 millimetre. A gas under pressure such as air is blownthrough this passage. The direction of blowing is indicated by thearrows 21,22. Facing the orifice through which the gas emerges is aplate of glass 3. During trials, it became clear that at a distance "d"of approximately 4 millimetres or less separating the orifice from theplate of glass 3, the said plate 3 experiences a suction force and tendsto be driven towards the cylinder 1. For a distance greater than the onejust mentioned, the jet of gas leaving the orifice of the cylinder 1tends to push the plate of glass 3 away. This position situated at adistance of approximately 4 millimetres can therefore be likened to aposition of unstable equilibrium. When the distance between the orificeand the plate of glass 3 is less than 4 mm, the said plate 3 istherefore sucked towards the cylinder 1; however, as the distancebetween the orifice and the plate 3 becomes less than approximately 0.2millimetres, the plate 3 then experiences a force of repulsion. Theposition of the plate 3, at a distance of approximately 0.2 millimetresaway from the orifice, may therefore be likened to a position of stableequilibrium. Indeed, if the relative positions of the cylinder 1 and ofthe plate 3 are altered slightly, the plate 3 will be repositioned in aposition of stable equilibrium either under the effect of a suctionforce when, for example, the cylinder 1 is moved slightly away from theplate 3, or under the effect of a force which tends to move the saidplate 3 away when, for example, the cylinder 1 is brought slightlycloser to the glass plate 3.

FIG. 2 represents a diagram, viewed from above, of a pusher 4 as may befound in the glassmaking industry. Such pushers 4 are especially usedfor bringing the bottles 5 which have just been manufactured from themoulding zone, as soon as they are released from the mould, towards aconveyor belt 7 which may, for example, take them towards an annealingtunnel, in the direction indicated by the arrow 23.

The movement of the pusher 4 towards its position 6 for bringing thebottles 5 onto the conveyor 7 is represented in this FIG. 2.

The subsequent figures illustrate in greater detail the inventionadapted to a pusher used for moving bottles which have just beenmanufactured.

A diagram, viewed from above, of part of a pusher is represented in FIG.3. The wall 8 of the pusher includes an orifice 9 through which a gasunder pressure emerges. The orifice 9 may be the end of a simple hole oralternatively of a slit. The other end 10 of the duct 11 is connected toa source, not represented, of gas under pressure. Trials were conductedusing a glass bottle 12 with a diameter of 80 millimetres facing theorifice 9. These trials were conducted with pressures ranging between 1and 5 bar, on the one hand when the duct 11 was a hole with a diameterof 2 millimetres, and on the other hand when the duct 11 was a slit 0.25millimetres wide and 20 millimetres tall, the slit being parallel to thevertical axis of the bottle. The results of these trials are illustratedby the curves represented in FIGS. 4 and 5. These curves represent theforce exerted on the bottle 12, expressed in Newtons, as a function ofthe distance "d" separating the bottle 12 from the orifice 9. Points onthese curves which have a positive ordinate-axis value correspond tosuction forces, and points which have a negative ordinate-axis valuecorrespond to pushing forces.

In the curves of FIG. 4 it is clear that as long as the distance islarge enough, the bottle 12 experiences a pushing force and is thereforemoved away from the wall 8 of the pusher. From a certain distance "d"corresponding to the point 13, and below this value, the bottle 12experiences a suction force which attracts it towards the wall 8. Thisdistance, which corresponds to a state of unstable equilibrium, in thecase of this trial was slightly less than 10 millimetres and can varydepending on the pressure. When this distance reaches the point 14corresponding to a value of approximately 0.1 millimetres, a value whichvaries as a function of the pressure, the bottle 12 again experiences apushing force which therefore prevents any contact between the wall 8and the bottle 12. This FIG. 4 shows that the pusher will be able tocause a bottle 12 to move along without the risk of damaging it becauseno contact between the wall 8 and the bottle 12 occurs. In effect, assoon as the bottle leaves the mould, a pusher advances towards the saidbottle. As soon as the point 13 of unstable equilibrium is exceeded, thebottle 12 experiences a suction force which brings it as close aspossible to the wall 8. As the pusher moves, the bottle graduallyreturns to a position of stable equilibrium with practically no contactwith the wall 8; there may nonetheless be some contact between the wall8 and the bottle 12, but this is only of a point-contact nature, forexample if the bottle tilts slightly as it moves along. The bottle 12 isthus held in place in an almost stable fashion close to the wall 8 inone of the compartments of the pusher which are provided for thispurpose. It is still possible to make the bottle be held more firmly asit is moved along by providing a second orifice, not represented in thefigures, through which a gas is also blown under pressure, the saidsecond orifice being situated on another wall of the pusherperpendicular to the wall 8. The bottle 12 can therefore be held firmlyin the corner formed by the two walls without having any contact withthe said walls of the pusher, the two orifices acting simultaneously onthe bottle 12.

The curves of FIG. 5 illustrate the same phenomenon when the duct 11 isa slit having a width of 0.25 millimetres and a height of 20 mm.

In the case of FIG. 3, and therefore of FIGS. 4 and 5, it was assumedthat the bottle 12 presented itself along the axis of the orifice 9.Now, it is quite obvious that when the bottles are released from themoulds, they may have positions which vary somewhat, even if this isonly on account of vibration due to the type of installation. FIG. 6illustrates the case of a bottle 12 presenting itself facing the orifice9 with a slight offset. This offset is represented in FIG. 6 by thedistance "e" which separates the axis 15 of the duct 11 from the axis 16of the bottle 12. Trials were also conducted according to thisconfiguration and these are shown in FIG. 7 in the case of a slit wherethe various curves correspond to various pressures; the distance "e" isapproximately 10 millimetres. The various curves show that despite theoffset "e", the same phenomenon occurs and therefore allows the bottle12 to be kept held firmly close to the wall 8 without any contact withthe latter which may lead to damage to the bottle 12.

The various results given in FIGS. 4, 5 and 7 show that this firstalternative form of the invention, illustrated in FIGS. 3 and 6, doesindeed lead to the desired result: that of keeping the bottle 12 heldfirmly close to the wall 8 while at the same time limiting contacttherewith. By contrast, in all cases, there is a region on the curveswhich corresponds to distances beyond the point of unstable equilibrium,where the bottles experience pushing forces. It therefore seems trickyto be able to bring a bottle 12 nearer without the risk of these forcesdestabilizing it, thus causing it to fall or even break. One solutionconsists in not starting to blow gas until the distance "d" separatingthe bottle 12 from the wall 8 corresponds to suction forces which willbe exerted on the said bottle 12. It was stated earlier that althoughsuch a solution is conceivable, it is by contrast complicated toimplement and has a high cost.

Another alternative form of the invention is illustrated in FIG. 8.According to this alternative form, the wall 8 has passing through it aslit through which a gas under pressure flows in the direction indicatedby the arrows 24,25, the said slit forming an angle with theperpendicular to the surface of the wall 8. Such a configuration, withan angle which has to be greater than a value defined as a function ofthe dimensions of the slit and of the pressure of the gas, creates aCoanda effect on the wall 8; that is to say that the flow of gas leavingthe slit runs along the surface of the wall 8 instead of coming out inthe direction of the axis 17 of the slit as would be expected. Such adevice therefore makes it possible, when a pusher advances towards abottle, for this bottle not to be pushed away because the flow of gas isnot pointing towards the bottle 12. This effect is illustrated in FIG. 9which represents curves corresponding to various gas pressures, this gaspassing through a slit 0.25 millimetres wide and 20 millimetres tall andmaking an angle of 45° with the perpendicular to the surface of the wall8. In these trials, the bottle was 80 mm in diameter and was situatedjust facing the air-output orifice of the slit, as indicated in FIG. 10.These curves show that the bottle 12 is continuously sucked towards thewall 8 as far as the point 18 of stable equilibrium beyond which thebottle 12 is pushed away. In the suction zone, when the distance isgreat, the suction is almost negligible but the curves show that itbecomes considerable when the distance "d" becomes smaller; indeed thesuction values for these curves are comparable with those of the curvesof FIGS. 4, 5 and 7. When the pusher is brought closer to the bottle 12,the latter therefore experiences suction forces which allow it to beheld firmly close to the wall 8, while at the same time avoiding contactwith the said wall 8.

FIG. 11 describes the same device as FIG. 10 but the bottle 12 has anoffset "e" with respect to the orifice of the slit. On measurement, thisoffset "e" was approximately 10 millimetres. The results of the trialscarried out with several gas pressures are given in FIG. 12, which showsthat even when a bottle is not presented directly facing the orifice,this alternative form according to the invention remains effective andallows the bottle 12 to be held firmly in the compartment provided forthis purpose in the pusher while at the same time limiting contact withthe wall 8 of the pusher as the pusher-bottle 12 assembly moves along.

In FIG. 11, the bottle 12 is offset with respect to the orifice but inthis configuration the bottle 12 faces the flow of gas leaving the slitwhich, because of the Coanda effect, runs along the wall 8. It is,however, possible for the bottle 12 to be offset with respect to theorifice in the other direction. Trials were conducted with various gaspressures in this configuration which is not represented in the figures.The results are shown in FIG. 13; the bottle 12 experiences forces ofsuction which pulls it towards the wall but no pushing force occurs. Toavoid contact which could arise, the invention envisages a second slitplaced on a wall perpendicular to the wall 8 so as to hold the bottle 12firmly in the corner formed by the two walls. The bottle 12 is thusbrought back into a position similar to the one in FIG. 10 as a resultof the suction due to the second slit.

The invention also envisages openings in at least one of the walls ofthe pusher to allow the flow of gas to discharge and avoid any risk ofturbulence. Such an embodiment is illustrated in FIG. 14. Twoperpendicular walls forming part of the pusher are represented in thisFIG. 14. The slit 19 blows air towards the corner formed by the twowalls, the air being discharged through the opening 20 provided on thesecond wall. When a bottle is present, the latter is sucked into andimmobilized in the corner of the pusher. Moreover, as the air isdischarged through the opening 20 it does not disturb the positioning ofthe said bottle. Likewise, when there are two slits placed on twoperpendicular walls, these will preferably be positioned at differentheights so that they do not interfere with each other.

A pusher 24 according to the invention is illustrated in FIG. 15. Thispusher 24 has two compartments in which two bottles 25,26 may be housed.Represented diagrammatically in the main wall 27, that is to say the onefacing the bottles, is the duct 28 through which compressed air isconveyed from the inlet 29 as far as the slits 30. The Coanda effectsymbolized by the arrows 31 occurs at the outlet of these slits. Thepushers also have walls or fingers 32 perpendicular to the wall 27 andforming compartments in which the bottles 25,26 are held as the pushermoves along. To avoid any direct contact with the walls, contactmaterials 33 are provided on each of the walls, and their function is tolimit any risk of damaging the glass.

FIGS. 16 and 17 show two extreme positions of the pusher 24 associatedwith the bottles 25,26. The inventors have been able to demonstrate thatwhile it was necessary to avoid as best possible any contact with thewalls of the pusher, it was also very important to guard againstcentrifugal force due to the movement of the pusher. It is especially toguard against this centrifugal force that the slits are placed on themain wall 27 of the pusher. Although it was seen earlier that it wasalso possible to provide additional slits on the walls or fingers 32,these additional slits could not be the only ones because the suctionwould then not be sufficient to combat the centrifugal force because oftheir positions.

The invention has been described more specifically for an applicationregarding pushers. However, the results obtained which consist inholding an article firmly, especially using suction forces, whilelimiting contacts with the wall of the mechanical tool are attractivefor other applications such as those mentioned earlier: device foraligning bottles on a conveyor, troughs for conveying gobs. In suchcases it is possible to provide different slits acting in succession onthe articles travelling past the wall of the tool; for example, bottlescan be aligned on a conveyor progressively by the successiveintervention of several orifices emitting a jet of gas, while thebottles are conveyed on a rolling belt.

I claim:
 1. Method of handling articles in which at least one mechanicaltool conveys the article or plays a part in transferring the article,characterized in that at least one jet of gas under pressure is blownthrough a duct passing through the mechanical tool, and in that thearticle is held in position on the mechanical tool while limitingcontact therewith by an air cushion between said article and said tool,by means of the said jet of gas.
 2. Method according to claim 1,characterized in that the articles are made of glass and are at a hightemperature while they are being handled.
 3. Method according to one ofclaim 1, characterized in that the blowing of gas starts when thearticle is a determined distance away from the mechanical tool. 4.Method according to one of claim 1, characterized in that the jet of gasis blown through a duct arranged relative to the wall of the mechanicaltool on which it emerges in such a way as to create a Coanda effect onthe wall of the mechanical tool.
 5. Method according to claim 4,characterized in that the gas flows in a direction similar to therelative path followed by the article with respect to the tool. 6.Method according to claim 1, characterized in that at least two jets ofgas are blown, these acting simultaneously or in succession on one andthe same article or on different articles.
 7. Device for handlingarticles including a mechanical tool for conveying an article or playinga part in transferring it, characterized in that at least one wall ofthe tool is pierced with at least one duct connected to a source of gasunder pressure to provide an air cushion between said article and saidtool, and in that the orifice of the said duct is placed such that thedistance separating it from the article decreases during at least afirst phase in the handling.
 8. Device according to claim 7,characterized in that the direction of the duct forms an angle with thesurface of the wall through which it passes in order to form a Coandaeffect with the emerging jet of gas.
 9. Device according to one ofclaims 7, characterized in that the orifice of the duct is a slit. 10.Device according to one of claims 7, characterized in that the orificeis composed of a set of holes.
 11. Application of the method accordingto claim 1 for the handling of bottles using a pusher.
 12. Applicationof the method according to claim 11, characterized in that the pusherincludes a main wall and perpendicular fingers and in that at least onejet of gas under pressure is blown through a duct passing through themain wall.
 13. Application of the method according to claim 1 for thealignment of bottles on a conveyor.
 14. Application of the methodaccording to claim 1 for the transportation of gobs.